Reporting this week at the annual American Geophysical Union, scientists from UC Irvine discussed air quality results from samples taken during the 2012 and 2013 Hajj.

The annual pilgrimage brings between 3-4 million people to the holy city of Mecca. Isobel Simpson, the lead researcher on this project, stated that, "The problem is that this intensifies the pollution that already exists. We measured among the highest concentrations [of smog-forming pollutants] our group has ever measured in urban areas – and we’ve studied 75 cities around the world in the past two decades.”

The worst locations were tunnels leading into the Grande Mosque where carbon monoxide levels were up to 300 times higher than baseline measurements, and pedestrians were often walking in large numbers alongside idling motor vehicles. Increases in carbon monoxide are linked to increased numbers of hospitalizations and deaths from heart failure. In addition to carbon monoxide, the team found elevated levels of benzene, black carbon, and other fine particulates that can affect lung function.

The main culprit here that can be addressed by the Saudi government is a lack of regulation over automobiles, gasolines, and exhausts. Currently, there is a significant lack of public transportation in the area, and nearly everyone owns a car. Those cars don't have the devices that are currently required and built into vehicles in the Unites States to limit pollution.

The easiest thing to fix would be separating pedestrians from cars in the tunnels, or at least spreading vehicles out more evenly among the tunnels leading to the Mosque, so that pollutants don't build up as much and negatively affect those walking in. Alternatively, improving ventilation in the tunnels would reduce deadly carbon monoxide build-up.

In the meantime, if you are planning to join the Hajj in the near-future, consider bringing an air-filtering face mask.

Greenpeace this week released a report on soil and rice crops sampled in villages close to a concentration of heavy metals smelters in China's Hunan Province, "an area that ranks first in rice output and among the top five in nonferrous metals production." The results showed that both rice and soil near the industrial complex are contaminated by heavy metals, including lead. "12 out of all 13 rice samples contained excessive levels of cadmium." Read the "Cadmium rice" report at Greenpeace East Asia. Here's a related piece at the New York Times.

The United States began phasing out the use of tetraethyllead in gasoline in the mid 1970s (though it's still used in aviation and race car fuel). The pollution from TEL-enhanced gas, however, continues to linger in the soil, especially in cities, where concentrations of tailpipe emissions were higher. A recent study of New York City chickens found that lead from the soil was showing up in detectable levels in the chickens' eggs. The dose is low (though you probably don't want young children eating lots of those eggs), but it's a great example of how the effects of pollution don't vanish just because the pollution ends.

When the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired this image on December 7, 2013, thick haze stretched from Beijing to Shanghai, a distance of about 1,200 kilometers (750 miles). For comparison, that is about the distance between Boston, Massachusetts, and Raleigh, North Carolina. The brightest areas are clouds or fog. Polluted air appears gray. While northeastern China often faces outbreaks of extreme smog, it is less common for pollution to spread so far south.

Drop a message-in-a-bottle into the Gulf of Mexico, somewhere near New Orleans, and, 10 years later, your missive has a high likelihood of ending up near Cuba — or northern France. The website Adrift uses data from a global system of floating buoys to show you how ocean currents carry things like plastic debris around the planet.

New York Times China correspondent Edward Wong describes his life in heavily polluted Beijing, where he no longer feels safe running outside and, in order to bike around town, dons a black air filter face mask that makes him "look like an Asian Darth Vader".

This excerpt from the new book, Toms River by Dan Fagin, has me instantly intrigued. The book is about one of the rare places where scientists were able to prove that not only was there a cluster of cancer cases, but that those cases could be linked to a cause. The excerpt explains why this is such a rare thing. Turns out, just because it looks like a town has more cancers than it should, doesn't mean that's always what's going on.

I'm honestly not sure which is weirder: That Clean Air Asia made an interactive map of air pollution that visualizes various cities' smog levels in terms of nose-hair length ... or the fact that thicker, more luxuriant nose hairs really do reduce your risk of asthma. The world is a strange place, people.

I was born in 1981 and, because of that, I largely missed the part of American history where our rivers were so polluted that they did things like, you know, catch fire. But it happened. And, all things considered, it didn't happen that long ago. The newspaper clippings above are from a 1952 fire on Ohio's Cuyahoga river. Between 1868 and 1969 that river burned at least 13 times.

That's something worth remembering — not just that we once let our waterways get that trashed, but also the fact that we've gone a long way towards fixing it. We took 200 years of accumulating sewage and industrial degradation and cleaned it up in the span of a single generation. At Slate, James Salzman writes about that reversal of environmental fortune, a shift so pronounced — and so dependent upon a functioning government in which a diverse spectrum of politicians recognize the importance of investing in our country's future — that it seems damned-near impossible today.

... discharging raw sewage and pollution into our harbors and rivers has been common practice for most of the nation’s history, with devastating results. By the late 1960s, Lake Erie had become so polluted that Time magazine described it as dead. Bacteria levels in the Hudson River were 170 times above the safe limit. I can attest to the state of the Charles River in Boston. While sailing in the 1970s, I capsized and had to be treated by a dermatologist for rashes caused by contact with the germ-laden waters.

In 1972, a landmark law reversed the course of this filthy tide. Today, four decades later, the Clean Water Act stands as one of the great success stories of environmental law. Supported by Republicans and Democrats alike, the act took a completely new approach to environmental protection. The law flatly stated there would be no discharge of pollutants from a point source (a pipe or ditch) into navigable waters without a permit. No more open sewers dumping crud into the local stream or bay. Permits would be issued by environmental officials and require the installation of the best available pollution-control technologies.

The waste flushed down drains and toilets needed a different approach, so the Clean Water Act provided for billions of dollars in grants to construct and upgrade publicly owned sewage-treatment works around the nation. To protect the lands that filter and purify water as it flows by, permits were also required for draining and filling wetlands.

At Grist, Jess Zimmerman has an interesting piece about a lake near a notoriously leaky former Soviet nuclear research site, where the radiation level is so high that an hour on the beach can be enough to kill you.

You can’t really blame Lake Karachay for acting up — it comes from a really rough area. The lake is located within the Mayak Production Association, one of the largest — and leakiest — nuclear facilities in Russia. The Russian government kept Mayak entirely secret until 1990, and it spent that period of invisibility mainly having nuclear meltdowns and dumping waste into the river. By the time Mayak’s existence was officially acknowledged, there had been a 21 percent increase in cancer incidence, a 25 percent increase in birth defects, and a 41 percent increase in leukemia in the surrounding region of Chelyabinsk. The Techa river, which provided water to nearby villages, was so contaminated that up to 65 percent of locals fell ill with radiation sickness — which the doctors termed “special disease,” because as long as the facility was secret, they weren’t allowed to mention radiation in their diagnoses.

Suzanne Paulson, UCLA professor of atmospheric and oceanic sciences, saw "Carmageddon" as an opportunity to make use of a "natural experiment." She and a colleague "measured pollutants in the air during the LA freeway shutdown last year, and have now released their findings.

Air quality near the normally busy highway improved by 83 percent that day last July, relative to comparable weekends. Elsewhere in West Los Angeles, the improvement was equally dramatic. Air quality improved by 75 percent on that side of the city and in Santa Monica, and by 25 percent throughout the entire region, as a measure of the drop in ultrafine particulate matter associated with tailpipe emissions.

"We saw what we expected: you take motor vehicles away, the air gets really, really clean," Paulson says, "which tells us that most of the pollution is from motor vehicles from one type or another in this area."

Nathan Kensinger is an artist "whose work explores hidden urban landscapes, off-limits structures, and other liminal spaces." He told me about a project that he, Laura Chipley, and Sarah Nelson Wright are working on called The Newtown Creek Armada:

It's a public art installation that is using remote control boats and underwater cameras to explore the Newtown Creek, a federal Superfund Site in New York City.

The installation opens this weekend, when we will be inviting the public to pilot our fleet of nine miniature boats, and to film their own voyage on the Newtown Creek. We will also be presenting several videos of our voyages that document the more polluted parts of the creek, which is home to the second largest oil spill in the United States, and has been used as a dumping ground for heavy industry and raw sewage for over 150 years. Despite this history, nature is slowly returning to the area, as we discovered on our voyages.

In the middle of the night, I dream that I am at the wheel of a great ship, sailing the Pacific Ocean. A hundred and fifty feet of steel, crowned with a dozen broad sails, forces itself forward through the waves. The rigging creaks with the roll of the ship. Water hisses along the lee rail. I adjust the wheel, peering at the binnacle to see our heading.

We’ve been at sea for nearly a week, and for weeks more we have no hope of seeing land. What we do hope to see, though, is something much rarer, something that amounts to a new and dark wonder of the world.

Dolphin carcasses are displayed by conservationists and environmental police officers at San Jose beach, 40kms north of Chiclayo, Peru, on April 6, 2012. The cause of death of over 800 dolphins in the last four months on the shores of Piura and Lambayeque are still being researched, Gabriel Quijandria, Deputy Environment Minister said on April 20, 2012. More about the ongoing investigation into the possible cause of these mass die-offs: CBS News, MSNBC, AFP, DPA, CNN, (REUTERS/Heinze Plenge)

Let me preface anything else in this post by clarifying something important. What we are talking about here is a hypothesis—it's not been proven. In fact, it's not even really been tested yet. The studies that will put the hypothesis to the test are currently underway. So please (please, please, please) do not walk away assuming this is a given. It's not. It could very well be completely and utterly wrong. But it's interesting. And it will be in the news. And I want you guys to hear about it in the proper context.

This idea is (for now) based on "what if" extrapolation rather than data. But it's not totally crazy. We know air pollution affects health in ways would not have been obvious just a few decades ago. For instance, there is a strong, well-documented connection between air pollution and heart disease. In 2009, Aruni Bhatnagar, professor of medicine at the University of Louisville, told me that studies from 250 different metropolitan areas in the United States showed that a spike in air pollution was reliably followed by a spike in cardiac deaths within next 24-48 hours. The people primarily at risk are those who already have underlying heart health problems, but it's not always clear who those people are. We don't yet know exactly how pollution affects the heart—it could well be a cascade of effects that actually starts in the lungs—but we can see that the affect is there.

This new hypothesis, proposed by Arne Astrup, head of the department of obesity and nutrition at the University of Copenhagen, does not come with that kind of supporting evidence. Instead, it's more of an extrapolation.

The idea proposes that breathing in extra CO2 makes blood more acidic, which in turn causes neurons that regulate appetite, sleep and metabolism to fire more frequently. As a result, we might be eating more, sleeping less and gaining more weight, partly as a result of the air we breathe.

...Obesity and its associated health risks have escalated dramatically in the last few decades. And even though just about everyone thinks the reason is obvious -- we are eating too many calories and exercising too little -- research has revealed that obesity is far more complex than that, with multiple genes, metabolic pathways and even gut microbes involved, said obesity researcher David Allison, director of the Nutrition Obesity Research Center at the University of Alabama at Birmingham.